1. Field of the Invention
The present invention relates to a rotor and a motor.
2. Description of the Related Art
Conventionally, a rotor was disposed at the inner side of an armature, that is, a so-called inner rotor type motor has been known in the past. The rotor used in an inner rotor type motor can be mainly classified into an SPM (Surface Permanent Magnet) type rotor wherein a plurality of magnets can be attached to an outer circumferential surface of the rotor core, and an IPM (Interior Permanent Magnet) type rotor wherein a magnet is filled inside the rotor core.
In a typical IPM type rotor, as in the SPM type rotor, each magnet is disposed so that a pair of magnetic pole surfaces are directed towards a radially outer side and a radially inner side. For this reason, only the magnetic pole surface on a radially outer side is used to operate the motor. Therefore, in recent years, in order to effectively utilize the magnetic pole surface of the magnet, each of a pair of magnetic pole surfaces of the magnet is arranged in a circumferential direction, thereby proposing a so-called spoke type rotor structure.
A conventional rotor in which a pair of magnetic pole surfaces of the magnet are disposed to face towards a circumferential direction is disclosed in Japanese Unexamined Patent Application Publication No. 2010-63285, for example. The rotor disclosed in Japanese Unexamined Patent Application Publication No. 2010-63285 is provided with a magnet having an approximately rectangular parallelepiped shape, disposed at regular intervals in the periphery of the axial part. Also, each magnet is disposed so that a pair of magnetic pole surfaces face towards a circumferential direction, and the neighboring magnets are arranged so that identical poles face each other.
As described in Japanese Unexamined Patent Application Publication No. 2010-63285, a magnetic pole surface is effectively utilized in a spoke type rotor structure. For this reason, comparing the spoke type rotor structure with an SPM type rotor or an IPM type rotor (other than the spoke type), given that they are configured to generate the same magnetic force, the spoke type rotor structure is the one capable of designing a smaller diameter for the rotor.
However, in the recent years, not only the miniaturization of a motor but also the improvement of a torque is being required. That is, it is required to increase the magnetic force of the rotor without increasing the diameter of the rotor.